30-January-2012

Home Theater Speaker Guide - 2.1 configuration




Fine-Tuning

Once you have done your basic speaker setup, you are ready to enjoy the home theater entertainment experience. Keep in mind, however, that every room is different; you may be able to further improve the sound by going beyond the general guidelines and fine-tuning the speaker placement within your room. You could, of course, hire a professional installer; however, with just a little time and some careful listening, you can do it yourself.

YOUR ENVIRONMENT

An Ongoing Experiment

There is no objectively perfect setup. All speakers, no matter how good, are bound by the laws of physics. What you can do is put them in the best locations to take maximum advantage of their capabilities, both individually and within the total system. Remember that the best sound is what sounds best to you. It is your system. If you have set it up and it sounds great, you may not need to read any further.

However, if you are not hearing any bass, or there is no sense of spaciousness and depth, or something seems to be missing, some fine-tuning may be in order. Even small adjustments in placement can have clearly audible effects. And that goes for your furnishings as well as your speakers.

First, do some extended listening. Do you hear a convincing sonic image between your main (front left and right) speakers? This is the soundstage, and you want to maximize it for depth and richness. Ideally, the speakers will disappear, and the sound will fill the space between them. Focus on different types of sounds - voices, motion, music, sound effects - in turn. Individual vocals or instruments, or effects such as footsteps, should be precisely placed across this space.

Now try positioning your main speakers farther apart and then closer together and listen to the results. Move the speakers in small increments, a few inches at a time. Generally, the greater the distance between your main speakers, the wider your soundstage; the closer they are, the more centered the sound. If the speakers are too far apart, they will start to sound like separate speakers rather than a coherent system.

Similarly, when fine-tuning the placement of the surrounds, keep the idea of the coherent system in mind.

Surround sounds should emanate from within a general area (covering the sides and rear of the room). Even if the surround sounds can be localized, the localization should be from within this overall area and not just from an individual speaker. The sonic image should be a single entity or environment.

Many of the more full-featured A/V receivers include a calibration microphone and can generate test tones for each speaker individually, then automatically calibrate distance, levels, and other settings. An increasingly popular receiver feature goes further, providing full and automatic room equalization. These features greatly simplify setting up your system properly.

Be aware of standing waves in your room, which are caused by sound waves reflecting off the walls. Because the reflections can overlap, the waves will cancel each other out at some spots (dips or null points) and reinforce each other at different spots (peaks). All rooms have standing waves, and they are most noticeable at low frequencies in smaller (and especially squarer) rooms. Play some music with strong, steady bass, and walk around the room. If you hear very little bass in some spots and lots of it in others, then you have a standingwave problem, and you want to be sure that your listening spot is not in a peak or dip. If it is, first try moving your subwoofer - even a few inches can make a difference. Similar shifts in the main speakers, or in room furnishing - even moving your listening spotmay help.

Let Nothing Come Between You and Your Sound

You want a clear path for the sound between your speakers and your listening position. If you have furnishings blocking your view of the speakers, you can be sure they are also blocking sound. The only exception here is the subwoofer, whose low - frequency sounds are omnidirectional and do not follow the line of sight rule.

Room Geometry

Room shape, ceiling height, and flooring material - all contribute to your room acoustics, its unique sound signature. While you probably can not redesign or rebuild your room, there are some things you can do to make the most of it.

First, try to minimize the areas of bare walls and floors, although that does not mean you need to cover every square inch. Keep the aesthetics of your room and the sound benefits of wall and floor coverings in balance. The idea is to have as much of the sound as possible reach your ears straight from the speaker - not from off your floor and walls. Reflected sounds reach your ears together with those coming directly from the speaker, reducing clarity. So the placement of rugs and wall coverings is as important as their coverage. Also, furnishings don not have to be soft and absorbent to minimize reflections. Bookshelves, for instance, can serve the same purpose by diffusing reflections.

Some of the biggest acoustic problems are caused by rooms that are perfectly square or have one dimension exactly twice another. These are the geometries that tend to generate standing waves that cause clarity and level issues. If this describes your room, you may need to perform extra experimentation with speaker and furniture placement to defeat the geometric odds.

The Multipurpose Home Theater

If, like most of us, your home theater room also is your living/family/workout room, then you may have to make a few allowances for your speakers. But sound can still be a top priority.

To avoid shaking and rumbling the whole house or disturbing your neighbors, you can place your subwoofer on rubber, dense foam, or neoprene pads to isolate it from the floor. (Many companies sell pads and platforms specifically for subwoofer isolation.) Also, make sure all your speakers are far enough away from intersecting room boundaries (wall and ceiling, wall and floor, and especially corners) to reduce boom - these areas naturally reinforce bass frequencies.

To ensure a home theater experience that is not dominated by dramatic sound effects at the expense of dialogue clarity, be sure to set the proper volume level for your center speaker. Turning up the overall volume to compensate for dialogue that is too soft will often overpower you with everything except dialogue. Most movies and TV shows are mixed with the bulk of the dialogue in the center channel, and proper level setting will keep it loud and clear.

All inall, your home theater can deliver great sound while still accommodating the other activities in your home.

A Bit About the Visual

Audio is not the only part of your home theater you will want to calibrate. Most TV sets will need calibration as well. Most TVs have been factory calibrated to look good in a retail showroom, whereas your lighting conditions and preferences are likely to be very different. Your furniture and decorations affect how you see your TV picture, too, so it is important to calibrate your visual settings - like brightness, contrast, and colors - for your room. As with audio, this can be done by a professional installer, for a fee. For much less, you can buy a calibration DVD to help you. These are available from a number of different manufacturers - ask your A/V equipment retailer or check the Web. This calibration will probably take half an hour to an hour, time well spent.

For the optimum viewing experience, check out the recommended viewing distance for various screen sizes and resolutions when choosing a TV set. Most manufacturers offer guidelines on this.

Original article from Dolby http://www.dolby.com

Go Back